(11:45AM - 1/29/20) A winter storm is expected to impact the state and region, Saturday through. This winter storm is expected to bring significant snowfall, with several inches of accumulation expected across portions of the state.
A winter storm is expected to impact the state and region Saturday through Sunday, and is expected to bring significant snowfall accumulation to portions of the state. The storm system will eject out into the Plains on Saturday, then moving eastward through the mid-Mississippi Valley and eventually Ohio Valley on Sunday. Model guidance has been showing the potential for a winter storm during this period for several days now. Model guidance has been and continues to be in good agreement overall regarding this event. However, here is a small amount of disagreement on where the heaviest axis of snowfall will set up. With this update we have introduced a corridor of 6-9" expected snowfall totals, otherwise little other changes were needed due to continued model continuity.
Snow is expected to spread into Northern Illinois late Saturday afternoon and evening. Snow of varying intensity will then continue through Sunday evening. The most significant period of snow will be from late Saturday afternoon through early Sunday morning. During this time periods of heavy snow will be possible, with high snowfall rates of 1-2" an hour likely at times. In addition to the snow, wind gusts of 30-40MPH will be possible, late Saturday afternoon evening through early Sunday day morning.
Additionally, lake enhancement is expected across Northeast Illinois during the event, with a small window for lake effect snow on the backside as the storm departs the region.
Precipitation will spread into Central Illinois between mid Saturday morning and mid Saturday afternoon. Precipitation will then continue through Sunday evening. Across Central Illinois for areas south of I-74, much of the precipitation will generally receive rain from the onset through Sunday morning. Beyond this time, areas of snow and snow showers are expected Sunday morning into Sunday evening. Across Central Illinois for areas along and north of I-74, this event will be mostly snow, outside of a mix at the onset.
Area of rain will first spread into Southern Illinois Saturday morning. Periods of rain will then continue through Sunday morning. As colder air wraps in, snow showers will become possible Sunday afternoon and evening, before precipitation exits the state.
A swath of snowfall totals of 4-7" is expected across Northern Illinois, with locally higher amounts possible. There will be a sharp gradient where snowfall totals rapidly taper across Central Illinois. This event is expected to feature lower than average snowfall ratios due to marginal temperatures, meaning it will be a heavy/wet snow.
Below are the snow and ice forecasts for this event.